For many reasons it is very useful to either caption your video or provide a written transcript of what is being said, expanding your audience by making the material much more accessible for students who may be hearing impaired, or watching the video with the sound turned down, when out and about on mobile devices where for whatever reason they don’t want to have earphones in.
Captioning takes time and may not always be appropriate. For instance, it is not helpful for screen casts showing text or videos of worked mathematical examples, since the caption text would distract from the text being written in the video. Captions should not occupy so much screen real estate that they obscure the content of the video.
Videos on social media have greater engagement when they are captioned. The autoplay feature of Facebook means people are less likely to scroll past if the first few seconds catch their attention, and the addition of captions can make this more likely.
The words don’t need to be verbatim but just given the gist of what is being said, including non-verbal cues (e.g. [laughter]) where appropriate. You may choose to use subtitles, which transcribe only what is being spoken in the video and would not include sounds (e.g. [door slams]).
Movie Maker – here’s a very short video that shows you how to add captions.
If you upload your videos to a YouTube channel, you can do it there. Youtube can add captions automatically but they are usually quite inaccurate.